In forming a wide variety of laminated structures, significant pressure must be exerted upon individual layers or sheets of a laminate while heat is applied to cure the bonding material between layers.
In the aircraft industry, autoclaves are conventionally used to mold composite laminated structures such as graphite/epoxy fibers which are employed to form panels for the exterior skin of an aircraft.
FIG. 1 shows a typical simplified schematic illustration of a molding apparatus for such a laminate. The laminate 10 is built up from layers of composite fiber material, such as preimpregnated graphite/epoxy, or other resin-reinforced composite material of the type conventionally available from CIBA-GEIGY Corporation or Hercules Corporation. The preimpregnated fabric layers are built up over a lower die 12, and a bagging film 14 is positioned over the laminate and die 12. In order to complete bonding between the layers of laminate 10, an autoclave (not shown) exerts substantial pressure against the laminate, via the bagging film, and the laminate is simultaneously subjected to heat. Vacuum ports 16 are provided in the die 12 to evacuate the volume beneath the bagging film 14 thereby allowing contraction of the bagging film and pressure transmission to the laminate 10. After a prescribed curing-bonding period, the bagging film is removed to allow removal of a molded laminate 10 that has the shape of die 12.
Although this prior art approach operates satisfactorily, it requires the use of an autoclave which is an extremely expensive piece of equipment. As a result, a manufactured laminate 10 is costly to manufacture. In addition, a time-consuming process is required for removing the bagging film and cleaning up die 12.